Add git_bool() for checking boolean git states

src/include/facts.sh

@@ -2,6 +2,29 @@
 
 . "$MKIT_DIR/include/ini.sh" || die "cannot import ini.sh"
 
+git_bool() {
+    #
+    # Get git bool (ie. exit status counts) $1
+    #
+    local bool_name="$1"
+    git_present || warn "can't give bool outside git repo: $bool_name"
+    case "$bool_name" in
+        dirty_files)
+            git diff-files | grep -qm 1 .
+            ;;
+        dirty_index)
+            git diff-index HEAD | grep -qm 1 .
+            ;;
+        dirty)
+            git_bool dirty_files || git_bool dirty_index
+            ;;
+        *)
+            warn "unknown git bool asked: $bool_name"
+            return 2
+            ;;
+    esac
+}
+
 git_fact() {
     #
     # Get git fact $1